A preferred application of the invention includes cleaning silicon (Si) membrane masks which are used, for example, in electron beam lithography to produce integrated circuits. In the lithographic process, particles whose diameter exceeds about 1/4 of the mask's line width have to be kept away from the mask. For a line width of 0.35 .mu.m this means that particles down to a size of about 100 nm adversely affect the lithographic process and, therefore, have to be removed. Previously known methods are unsuitable for this purpose, as the adhesion forces occurring with such small particles are high relative to their size. Larger particles (&gt;1000 nm) are removed by rinsing with a liquid or a gas jet, or are kept away by such means.
In photolithographic processes, thin transparent foils, so-called pellicles, may be positioned at a short distance above the mask to keep particles away from the mask. However, in lithographic processes using electron or ion beams no material objects must be introduced into the beam path. In addition, owing to the desired, and possibly, smaller line widths, such processes are adversely affected by particles that are even smaller than those occurring in photolithographic processes. Similar problems are encountered, for example, in medicine or chemistry, say, for catalysis, and generally in conjunction with any applications where extremely clean surfaces have to be produced, processed or treated.